Suppresses Prostate Cancer Cell Growth Research Articles

Inhibition of human prostate cancer cells proliferation by a selective alpha1-adrenoceptor antagonist labedipinedilol-A involves cell cycle arrest and apoptosis

In this research, we conducted an in vitro analysis to evaluate the prostate cancer cells response to labedipinedilol-A in order to determine the effect of this selective α 1-adrenoceptor antagonist to suppress prostate cancer cell growth by affecting cell proliferation and apoptosis. Here, we report that treatment of androgen-sensitive (LNCaP) and androgen-insensitive (PC-3) prostate cancer cells with labedipinedilol-A inhibited cell proliferation in concentration-dependent and time-dependent manners. Moreover, norepinephrine-stimulated proliferation of both cell lines are markedly inhibited by labedipinedilol-A. The probable involvement of α 1-adrenoceptors in this cellular response is suggested. Labedipinedilol-A-induced growth inhibition was associated with G 0/G 1 arrest, and G 2/M arrest depending upon concentrations. Cell cycle blockade was associated with reduced amounts of cyclin D1/2, cyclin E, Cdk2, Cdk4, and Cdk6 and increased levels of the Cdk inhibitory proteins (Cip1/p21 and Kip1/p27). In addition, labedipinedilol-A also induced apoptosis in PC-3 cells, as determined by using Hoechst 33342 staining, DNA fragmentation, and Annexin V staining assay. Furthermore, labedipinedilol-A triggered the mitochondrial apoptotic pathway, as indicated by increasing the expression of Bax, but decreasing the level of Bcl-2, resulting in mitochondrial membrane potential loss, cytochrome c release, and activation of caspase-9 and -3. We further investigated the role of MAPK cascades in the anti-proliferative and apoptosis effects of labedipinedilol-A, and confirmed that labedipinedilol-A could activate JNK1/2 but not p38 in both cell lines. Unlike JNK1/2, however, labedipinedilol-A treatment resulted in down-regulation of phospho-ERK1/2 expression. We concluded that labedipinedilol-A possessed the growth-suppressive and apoptotic effects on LNCaP and PC-3 cells by its α 1-adrenoceptor blockade, and the apoptotic effects of labedipinedilol-A primarily through caspases and MAPKs mediated pathways.

188 POSTER Leucinostatins suppress prostate cancer cell growth through the tumour-stromal cell interactions

188 POSTER Leucinostatins suppress prostate cancer cell growth through the tumour-stromal cell interactions

Protoapigenone, a Novel Flavonoid, Induces Apoptosis in Human Prostate Cancer Cells through Activation of p38 Mitogen-Activated Protein Kinase and c-Jun NH2-Terminal Kinase 1/2

In this study, we investigated the anticancer effect of protoapigenone on human prostate cancer cells. Protoapigenone inhibited cell growth through arresting cancer cells at S and G(2)/M phases as well as inducing apoptosis. Blockade of cell cycle by protoapigenone was associated with an increase in the levels of inactivated phospho (p)-Cdc25C (Ser216) and a decrease in the levels of activated p-cyclin B1 (Ser147), cyclin B1, and cyclin-dependent kinase (Cdk) 2. Protoapigenone triggered apoptosis by increasing the levels of cleaved poly(ADP-ribose) polymerase and caspase-3. In addition, activation of p38 mitogen-activated protein kinase (MAPK) and c-Jun NH2-terminal kinase (JNK)1/2 was a critical mediator in protoapigenone-induced cell death. Inhibition of the expression of p38 MAPK and JNK1/2 by pharmacological inhibitors or specific small interfering RNA reversed the protoapigenone-induced apoptosis through decreasing the level of cleaved caspase-3. In contrast, p38 MAPK, but not JNK1/2, was involved in the protoapigenone-mediated S and G(2)/M arrest by modulating the levels of Cdk2 and p-Cdc25C (Ser216). Moreover, in vivo xenograft study showed that protoapigenone had a significant inhibition of prostate tumor growth without major side effects on the mice we tested. This inhibition was associated with induction of apoptosis and activation of p38 MAPK and JNK1/2 in protoapigenone-treated tumor tissues. In conclusion, our results demonstrated protoapigenone suppressed prostate cancer cell growth through the activation of p38 MAPK and JNK1/2, with the potential to be developed as a chemotherapeutic agent for prostate cancer.

Ras Promotes Growth by Alternative Splicing-Mediated Inactivation of the KLF6 Tumor Suppressor in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the fifth most prevalent cancer worldwide and the third most lethal. Dysregulation of alternative splicing underlies a number of human diseases, yet its contribution to liver cancer has not been explored fully. The Krüppel-like factor 6 (KLF6) gene is a zinc finger transcription factor that inhibits cellular growth in part by transcriptional activation of p21. KLF6 function is abrogated in human cancers owing to increased alternative splicing that yields a dominant-negative isoform, KLF6 splice variant 1 (SV1), which antagonizes full-length KLF6-mediated growth suppression. The molecular basis for stimulation of KLF6 splicing is unknown. In human HCC samples and cell lines, we functionally link oncogenic Ras signaling to increased alternative splicing of KLF6 through signaling by phosphatidylinositol-3 kinase and Akt, mediated by the splice regulatory protein ASF/SF2. In 67 human HCCs, there is a significant correlation between activated Ras signaling and increased KLF6 alternative splicing. In cultured cells, Ras signaling increases the expression of KLF6 SV1, relative to full-length KLF6, thereby enhancing proliferation. Abrogation of oncogenic Ras signaling by small interfering RNA (siRNA) or a farnesyl-transferase inhibitor decreases KLF6 SV1 and suppresses growth. Growth inhibition by farnesyl-transferase inhibitor in transformed cell lines is overcome by ectopic expression of KLF6 SV1. Down-regulation of the splice factor ASF/SF2 by siRNA increases KLF6 SV1 messenger RNA levels. KLF6 alternative splicing is not coupled to its transcriptional regulation. Our findings expand the role of Ras in human HCC by identifying a novel mechanism of tumor-suppressor inactivation through increased alternative splicing mediated by an oncogenic signaling cascade.

Wwox Suppresses Prostate Cancer Cell Growth through Modulation of ErbB2-Mediated Androgen Receptor Signaling

The expression of the WWOX tumor suppressor gene is lost or reduced in a large fraction of various cancers, including prostate cancer. We previously reported that Wwox overexpression induced apoptosis and suppressed prostate cancer growth in vitro and in vivo. In this study, pathways through which Wwox contributes to control of prostate cancer cell growth have been investigated. We found that Wwox interacts with Ap2gamma and prevents it from entering the nucleus to bind the ERBB2 promoter region to activate transcription of ERBB2, a mediator of androgen receptor activity and prostate cancer cell growth at limiting androgen concentration. Ectopic expression of Wwox reduced ErbB2 protein expression in vitro and expression of Wwox protein inversely correlated with expression of ErbB2 protein in prostate cancer tissues. Furthermore, Wwox suppressed Ap2gamma/ErbB2-induced prostate cancer cell growth and suppressed prostate-specific antigen secretion through interaction with Ap2gamma and down-modulation of ErbB2, an effect that required functional androgen receptor.

The Immunophilin Ligands Cyclosporin A and FK506 Suppress Prostate Cancer Cell Growth by Androgen Receptor-Dependent and -Independent Mechanisms

The androgen receptor (AR) contributes to growth of prostate cancer even under conditions of androgen ablation. Thus, new strategies to target AR activity are needed. The AR interacts with the immunophilin FK506-binding protein 52 (FKBP52), and studies in the FKBP52 knockout mouse have shown that this protein is essential to AR activity in the prostate. Therefore, we tested whether the immunophilin ligand FK506 affected AR activity in prostate cancer cell lines. We also tested the hypothesis that the AR interacts with another immunophilin, cyclophilin 40 (Cyp40), and is regulated by its cognate ligand cyclosporin A (CsA). We show that levels of FKBP52, FKBP51, Cyp40, and a related co-chaperone PP5 were much higher in prostate cancer cells lines [(LNCaP), PC-3, and DU145] compared with primary prostate cells, and that the AR of LNCaP cells can interact with Cyp40. In the absence of androgen, CsA caused inhibition of cell growth in the AR-positive LNCaP and AR-negative PC-3 and DU145 cell lines. Interestingly, FK506 only inhibited LNCaP cells, suggesting a dependence on the AR for this effect. Both CsA and FK506 inhibited growth without inducing apoptosis. In LNCaP cells, CsA completely blocked androgen-stimulated growth, whereas FK506 was partially effective. Further studies in LNCaP cells revealed that CsA and FK506 were able to block or attenuate several stages of AR signaling, including hormone binding, nuclear translocation, and activity at several AR-responsive reporter and endogenous genes. These findings provide the first evidence that CsA and FK506 can negatively modulate proliferation of prostate cells in vitro. Immunophilins may now serve as new targets to disrupt AR-mediated prostate cancer growth.

823: Tocopherol Associated Protein Suppresses Prostate Cancer Cell Growth by Inhibition of the PI3 Kinase Pathway

You have accessJournal of UrologyDiscussed Poster, Monday, May 22, 2006, 1:00 - 4:00 pm1 Apr 2006823: Tocopherol Associated Protein Suppresses Prostate Cancer Cell Growth by Inhibition of the PI3 Kinase Pathway Jing Ni, Xingqiao Wen, Jorge L. Yao, Yi Yin, Min Zhang, Shaozhen Xie, Ming Chen, Brenna Simons, Anthony Disant'agnese, Edward M. Messing, and Shuyuan Yeh Jing NiJing Ni More articles by this author , Xingqiao WenXingqiao Wen More articles by this author , Jorge L. YaoJorge L. Yao More articles by this author , Yi YinYi Yin More articles by this author , Min ZhangMin Zhang More articles by this author , Shaozhen XieShaozhen Xie More articles by this author , Ming ChenMing Chen More articles by this author , Brenna SimonsBrenna Simons More articles by this author , Anthony Disant'agneseAnthony Disant'agnese More articles by this author , Edward M. MessingEdward M. Messing More articles by this author , and Shuyuan YehShuyuan Yeh More articles by this author View All Author Informationhttps://doi.org/10.1016/S0022-5347(18)33059-3AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail "823: Tocopherol Associated Protein Suppresses Prostate Cancer Cell Growth by Inhibition of the PI3 Kinase Pathway." The Journal of Urology, 175(4S), pp. 265–266 © 2016 by American Urological AssociationFiguresReferencesRelatedDetails Volume 175Issue 4SApril 2006Page: 265-266 Advertisement Copyright & Permissions© 2016 by American Urological AssociationMetricsAuthor Information Jing Ni More articles by this author Xingqiao Wen More articles by this author Jorge L. Yao More articles by this author Yi Yin More articles by this author Min Zhang More articles by this author Shaozhen Xie More articles by this author Ming Chen More articles by this author Brenna Simons More articles by this author Anthony Disant'agnese More articles by this author Edward M. Messing More articles by this author Shuyuan Yeh More articles by this author Expand All Advertisement PDF downloadLoading ...

Tocopherol-Associated Protein Suppresses Prostate Cancer Cell Growth by Inhibition of the Phosphoinositide 3-Kinase Pathway

Epidemiologic studies suggested that vitamin E has a protective effect against prostate cancer. We showed here that tocopherol-associated protein (TAP), a vitamin E-binding protein, promoted vitamin E uptake and facilitated vitamin E antiproliferation effect in prostate cancer cells. Interestingly, without vitamin E treatment, overexpression of TAP in prostate cancer cells significantly suppressed cell growth; knockdown of endogenous TAP by TAP small interfering RNA (siRNA) in nonmalignant prostate HPr-1 cells increased cell growth. Further mechanism dissection studies suggested that the tumor suppressor function of TAP was via down-regulation of phosphoinositide 3-kinase (PI3K)/Akt signaling, but not by modulating cell cycle arrest or androgen receptor signaling. Immunoprecipitation results indicated that TAP inhibited the interaction of PI3K subunits, p110 with p85, and subsequently reduced Akt activity. Constitutively active Akt could negate the TAP-suppressive activity on prostate cancer cell growth. Moreover, stable transfection of TAP in LNCaP cells suppressed LNCaP tumor incidence and growth rate in nude mice. Furthermore, TAP mRNA and protein expression levels were significantly down-regulated in human prostate cancer tissue samples compared with benign prostate tissues as measured by reverse transcription-PCR, in situ hybridization, and immunohistochemistry. Together, our data suggest that TAP not only mediates vitamin E absorption to facilitate vitamin E antiproliferation effect in prostate cancer cells, but also functions like a tumor suppressor gene to control cancer cell viability through a non-vitamin E manner. Therefore, TAP may represent a new prognostic marker for prostate cancer progression.

Targeted Inhibition of the KLF6 Splice Variant, KLF6 SV1, Suppresses Prostate Cancer Cell Growth and Spread

Prostate cancer is a leading cause of cancer death in men. Risk prognostication, treatment stratification, and the development of rational therapeutic strategies lag because the molecular mechanisms underlying the initiation and progression from primary to metastatic disease are unknown. Multiple lines of evidence now suggest that KLF6 is a key prostate cancer tumor suppressor gene including loss and/or mutation in prostate cancer tumors and cell lines and decreased KLF6 expression levels in recurrent prostate cancer samples. Most recently, we identified a common KLF6 germ line single nucleotide polymorphism that is associated with an increased relative risk of prostate cancer and the increased production of three alternatively spliced, dominant-negative KLF6 isoforms. Here we show that although wild-type KLF6 (wtKLF6) acts as a classic tumor suppressor, the single nucleotide polymorphism-increased splice isoform, KLF6 SV1, displays a markedly opposite effect on cell proliferation, colony formation, and invasion. In addition, whereas wtKLF6 knockdown increases tumor growth in nude mice >2-fold, short interfering RNA-mediated KLF6 SV1 inhibition reduces growth by approximately 50% and decreases the expression of a number of growth- and angiogenesis-related proteins. Together, these findings begin to highlight a dynamic and functional antagonism between wtKLF6 and its splice variant KLF6 SV1 in tumor growth and dissemination.

Effects on growth suppression of prostate cancer cell lines by rubber attachment with honeycomb structure: A proposal of an wearable anti-cancer device

4779 Background: An increased incidence of prostate cancer prompted us to find a possible new therapeutic modality without chemotherapy, irradiation, nor surgical intervention. We examined the effect of the rubber with honeycomb structure (Bio Rubber™: Yamamoto Co., Osaka, Japan) on human prostate cancer cells. Bio Rubber, containing highly purified lime stone and titanium powder, radiates infrared wave. Methods: Three prostate cancer cell lines, Du145, LNCap, and PC3, grown in culture dishes, were sandwiched by a set of Bio Rubber, and mRNA expression was analyzed by a human 1.2k cDNA microarray (Clontech). The results were analyzed by using GeneSpring program (Silicon Genetics, Redwood, CA, U.S.A). Morphological changes were also observed, and cells cultured without Bio Rubber attachment were served as controls. For the observation of growth suppression with Bio Rubber, cells were treated with sodium butyrate (SB), an histone deacetylase inhibitor that induces cell differentiation, with or without Bio Rubber attachment in another set of experiment. Results: mRNAs up-regulation higher than 1.4-fold in Du145 cells after 21-day-attachment of Bio Rubber were Fas (1.4 X), FasL(2.3 X), CASP1 and 10 (both 1.7 X), TRADD (1.4 X), and DFF40 (1.7 X); in LNCap, Fas (1.6 X), and CASP8 (1.6 X); in PC3, CD40 (1.4 X), and TNF (1.4 X), indicating that apoptotic pathways were stimulated in a various degree. Several apoptotic features such as mitochondrial condensation and cytoplasmic vacuolization were also observed. Growth suppression rate of Du145 on day 8 was 56 % with Bio Rubber, 78% with 2 mM SB, and 91% in combination; of LNCap, 52%, 35%, and 73%; of PC3, 59%, 0%, and 88%, showing that growth suppression effect of Bio Rubber was enhanced by SB. Conclusions: Bio Rubber attachment suppressed prostate cancer cell growth probably through stimulation of apoptotic pathways, and additive effects were observed in combination with SB. No significant financial relationships to disclose.

Emodin Down-Regulates Androgen Receptor and Inhibits Prostate Cancer Cell Growth

Hormone-refractory relapse is an inevitable and lethal event for advanced prostate cancer patients after hormone deprivation. A growing body of evidence indicates that hormone deprivation may promote this aggressive prostate cancer phenotype. Notably, androgen receptor (AR) not only mediates the effect of androgen on the tumor initiation but also plays the major role in the relapse transition. This provides a strong rationale for searching new effective agents targeting the down-regulation of AR to treat or prevent advanced prostate cancer progression. Here, we show that emodin, a natural compound, can directly target AR to suppress prostate cancer cell growth in vitro and prolong the survival of C3(1)/SV40 transgenic mice in vivo. Emodin treatment resulted in repressing androgen-dependent transactivation of AR by inhibiting AR nuclear translocation. Emodin decreased the association of AR and heat shock protein 90 and increased the association of AR and MDM2, which in turn induces AR degradation through proteasome-mediated pathway in a ligand-independent manner. Our work indicates a new mechanism for the emodin-mediated anticancer effect and justifies further investigation of emodin as a therapeutic and preventive agent for prostate cancer.

Antiandrogen-like actions of an antioxidant on survivin, Bcl-2 and PSA in human prostate cancer cells

Background: Androgens, while essential for prostate gland development, have been postulated to contribute to carcinogenesis, and antioxidants have been postulated to suppress prostate cancer development. We theorized that antioxidants might suppress prostate cancer cell growth by blocking androgen effects on cell survival. This hypothesis was tested by in vitro studies conducted in ALVA-101, an androgen responsive human prostate cancer cell line. Methods: ALVA-101 was cultured with or without testosterone (T, 10 −12 M) and pyrrolidinedithiocarbamate (PDTC, 10 μg/mL). Cell Titer 96 AQ, electrophoretic mobility shift assay (EMSA), reverse transcription-polymerase chain reaction (RT-PCR), Northern and Western blot were used to quantify the cell growth, nuclear factor-kappa B (NF-κB) activity, mRNAs of survivin, Bcl-2, androgen receptor (AR) and prostate specific antigen (PSA), and proteins of AR and survivin. Results: PDTC suppressed EMSA of NF-κB and significantly decreased ( p < 0.05) T's stimulatory effects on cell growth, mRNAs of survivin, Bcl-2, AR and PSA and synthesis of proteins of AR and survivin. Antisense to both survivin and Bcl-2 suppressed cell growth. Conclusions: PDTC, a potent inducer of apoptosis, exerts antiandrogen-like action by reducing AR protein and reversing the stimulatory effects of androgen on potent inhibitors of apoptosis.

Androgen suppresses PML protein expression in prostate cancer CWR22R cells

The ability of PML to modulate key suppressive pathways in tumor cells suggests that PML may act as a tumor suppressor. The detailed mechanism of how PML functions in prostate cancer progression, however, remains unknown. Here we demonstrate that in the presence of androgen, PML protein expression can be suppressed in CWR22R prostate cancer cells. Further studies reveal that PML can selectively suppress AR transactivation and PML protein expression positively correlates with increased p21 protein level and enhances p53 transcription ability in CWR22R cells. We also found that PML strongly inhibits CWR22R cell colony formation, while PML siRNA enhances AR activity and CWR22R cell colony formation. Together our results suggest that PML may suppress prostate cancer cell growth by inhibiting AR transactivation and/or enhancing p53 activity.

Partial growth suppression of human prostate cancer cells by the Krev-1 suppressor gene.

A series of functional studies were performed to assess the potential role of the ras-related transformation suppressor gene, Krev-1, in suppressing prostate cancer cell growth. Three human prostate cancer cell lines, PC-3, TSU-Pr1, and DU-145 were transfected with a plasmid containing the Krev-1 cDNA and a neomycin resistance gene. Selected G418-resistant clones were isolated and expanded into cell lines. All cloned transfectants exhibited a significant reduction in their in vitro growth rates, i.e., longer doubling times, when compared to the parental cell lines. Molecular analysis of the Krev-1 cloned transfectants revealed that they all contained variable copy numbers of the Krev-1 gene and expressed high levels of Krev-1 mRNA transcript, as shown by Southern and Northern analysis, respectively. To determine whether the biological properties associated with tumorigenicity were changed in these Krev-1 transfectants, their growth characteristics were examined on the basis of their ability to a) form colonies in soft agar, and b) produce tumors in SCID mice. The majority of the Krev-1 transfectants from the PC-3 and TSU-Pr1 cell lines showed a substantially reduced ability to form colonies in soft agar and produced significantly smaller tumors when inoculated into SCID mice. In contrast, there was no significant reduction in the soft agar colony-forming ability or in vivo tumorigenicity of the DU-145 Krev-1 transfectants. These results suggest that the Krev-1 suppressor gene induces partial suppression of the malignant phenotype of human prostate cancer cells containing activated ras oncogenes.